Storage of Cereals and the Challenges of Gas Monitoring

The ability to guarantee food supplies is an issue of increasing importance. As the global population continues to grow and while climate change and ocean acidification create problems for crops and fish stocks, food security represents a major challenge for many countries.1

When addressing the issue of food security, it is vital to consider not only global food production, but also food storage and preservation.

Cereals are one of the most significant sources of calories for the global population. Maize, rice and wheat provide upwards of 30% of the total calories consumed for more than 4.5 billion people, with citizens of developing countries most likely to be reliant on these kinds of crop.2

However, these types of crops are vulnerable to many issues during storage and can suffer damage from humidity, insects or microorganisms, causing crops to decline and risking wastage.3 Estimates state that in the developing world, insects and microorganisms cause the waste of around $500 million to $1 billion of maize annually.4

As a result, improvements to cereal storage methods to reduce losses are vital, both for economic reasons and to ensure human wellbeing. In the past, invasive insects and microorganisms have often been tackled using fumigants or gaseous pesticides in barns.

However, a more popular method in recent times has been to employ modified atmospheric conditions. This allows for the same level of protection for crops, with lower risks to health and safety.5

Modified Atmospheric Conditions

In a modified or controlled atmosphere, the usual ratio of gases found in the air is exchanged for a deliberately chosen combination of gases, often with food preservation in mind.6

In food packaging and transport, these modified atmospheres are now a common feature, employed to offer greater lifespans and higher quality of produce, including meat and fruit, lessening the need for preservatives.

The environment chosen for storage of grains is usually partly made up of carbon dioxide, nitrogen and oxygen. Higher levels of carbon dioxide with lower oxygen can create a fatal environment for insects, while higher levels of nitrogen and oxygen can work to manage the environment’s humidity, leading to lower levels of deterioration of crops and lessening the risk of spoilage.7

Nevertheless, the chemical make-up of the atmosphere in a grain bin is subject to fluctuations. Respiration of molds and insects can result in increased levels of carbon dioxide8, while stored seeds and cereals generate low levels of not only carbon dioxide, but also highly noxious carbon monoxide gas.9

It may in fact be more effective to monitor rates of carbon dioxide production in the storage area to detect spoilage at an early stage, as opposed to checking other conditions such as temperature.10

Gas Monitoring

Fast-acting online sensors with high sensitivity are vital in ensuring that wastage is kept to a minimum by making sure that atmospheric conditions are maintained within their ideal ranges, and ensuring heightened levels of carbon dioxide production, indicating spoilage, are detected early.

Edinburgh Sensors produces a varied range of infra-red based sensors and monitors, which are appropriate for use in the usual conditions experienced in grain silos or barges. Units on offer include the Gascard11, the Guardian NG12 and the GasCheck13, with a number of these being appropriate for detection of carbon dioxide, carbon monoxide and other hydrocarbon gases.

With four decades of experiences in designing and producing gas monitors, Edinburgh Sensors provides technical support and guidance alongside every purchase, as well as the option for custom solutions as needed.

Considering the difficulties faced in managing potential humidity levels in the cereal storage space, as well as the necessity for accuracy for several varying carbon dioxide concentrations, for example, if increased carbon dioxide levels are being employed to subdue insect populations, the Gascard NG11 represents the ideal solution for potential gas monitoring needs.

Humidity (in conditions between 0 – 95%) and relative humidity have no impact on measurements, and to make certain that carbon dioxide levels are measured with precision, regardless of variations in the immediate environment, the inbuilt pressure and temperature sensors can offset any fluctuations.

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The Gascard NG is able to measure CO2 concentrations of between 0 – 5000 ppm. It is also offered in the form of the Boxed Gascard13, which has a convenient exterior housing for instant installation and is connected by USB for constant data logging and monitoring.

The response time is under 10 seconds, making it a rapid and reliable method to begin gathering data on storage conditions.

With a built-in screen and set-up menus, installation is simple, and an integrated alarm allows the gas monitor to be part of an early warning system, keeping product losses to a minimum.

Since each of Edinburgh Sensors’ pioneering infra-red detectors boasts sensors able to manage a wide range of environmental conditions for long or short term storage, they are appropriate for use in the government, trader or farm cereal storage sites.